1. Field of the Invention
The present invention relates to a connecting structure for concrete block which is useful to connect concrete blocks at construction sites and a connector to be used in this connecting structure.
2. Description of the Prior Art
Concrete blocks which are used for building concrete structures such as beams, retaining walls, covered conduits (culverts) and aqueducts are manufactured at locations other than construction sites for enhancing working efficiencies, precisions and quality control levels. When the concrete blocks themselves are large and heavy or have complicated forms, however, they not only increase burdens imposed on transportation works and costs but also require large storage spaces.
Accordingly, it is practiced in these days to preliminarily manufacture the concrete blocks in divided forms, carry these divided blocks to construction sites and connect these divided blocks as occasion demands. For example, a block for a covered conduit which has a predetermined form is preliminarily manufactured as divided upper and lower blocks 201 and 202, and the divided blocks 201 and 202 are connected to each other at a construction site.
Cavities 201a and 202a are formed at intervals in ends of connecting side surfaces of the divided blocks 201 and 202. Further, ends 201b and 202b of internal reinforcement buried in the blocks are exposed in the cavities 201a and 202a.
To couple the divided blocks 201 with 202, the two divided blocks 201 and 202 are combined as shown in the drawing with a packing (not shown) interposed. These divided blocks 201 and 202 are integrated by welding the ends 201b and 202b of the internal reinforcement respectively which are opposed to each other.
However, the connecting method described above requires a prettily long time to complete a series of connecting works even when a plurality of welding workers are engaged with the works since five to ten minutes is necessary to weld the ends of the internal reinforcements at one location, and tends to allow welding qualities to be variable dependently on environmental conditions and abilities of workers.
Further, the packing cannot be sufficiently pressed at the connecting stage simply by welding the ends 201b and 202b of the internal reinforcement to each other. In other words, the two divided blocks 201 and 202 can hardly be connected in an adequate pressure contact condition with the packing interposed, thereby making it difficult to maintain expected airtightness and watertightness.